1. Field of the Invention
The present invention relates to an organic electroluminescent (hereinafter EL) device, and more particularly, to an organic EL display control system.
2. Description of Related Art
FIG. 1 is a schematic block diagram illustrating a typical display control system. As shown in FIG. 1, the display control system, to be used with, for example, a cellular phone, includes a display panel 10 and a driver controller 20. The display panel 10 includes a common terminal and a segment terminal. The driver controller 20 includes a common driver circuit 21, a segment driver circuit 22, a display RAM 23, a page address generating circuit 24, a data latch circuit 25, a line address generating circuit 26, a column address generating circuit 27, and a controller 28. At this point, the display RAM 23 has a cell matrix of 24-bit×24-bit as an example, and therefore, the data latch circuit 25 is a 24-bit data latch circuit.
The common driver circuit 21 is connected to the common terminal of the display panel 10 to be used as a scanning unit to scan a display region of the display panel, and the segment driver circuit 22 is connected to the segment terminal of the display panel 10 to be used as a data transmission unit. The page address generating circuit 24 is connected to the display RAM 23 through address buses and serves to designate a page address during a write operation. The data latch circuit 25 is connected to the display RAM 23 through data buses so that 24-bit data of a row may be output from the display RAM 23 at a time during a read operation. The line address generating circuit 26 is connected to the display RAM 23 through address buses (not shown) and serves to designate or select a row to be displayed during a read operation. The column address generating circuit 27 is connected to the display RAM 23 through address buses (not shown) and serves to designate a column address during a write operation. The controller 28 serves to control all components of the driver controller 20.
The display control system having such a configuration has common lines on right and left hands of the display panel 10 and segment lines on a lower portion of the display panel 10, and therefore, the driver controller 20 is designed to satisfy such an arrangement. Therefore, the driver controller 20 is further away from the common terminal than from the segment terminal.
Meanwhile, there are organic EL devices in which the common terminal is changed in position with the segment terminal because a driving voltage and power consumption are improved.
FIG. 2 is a schematic block diagram illustrating a conventional organic EL display control system. As shown in FIG. 2, except for the fact that the common terminal is changed in position with the segment terminal, the conventional organic EL display control system has the same configuration and arrangement as the display control system of FIG. 1.
Hereinafter, an operation of the organic EL display control system is explained in detail with reference to FIGS. 1 and 2.
First, for the write operation, a page address and a column address of the RAM 23 are designated through the page address generating circuit 24 and the column address generating circuit 27, respectively. In FIG. 2, the page address is designated as “0”, and the column address is designated as “2”. The display RAM 23 is configured so that data of 8 lines corresponding to one column (i.e., 8-bit data) may be written at a time. The controller 28 writes 8-bit data at a time on the designated page address and the designated column address, i.e., a page “0” and a column 2. In other words, when 8-bit data is transferred and a write command is received, 8-bit data is written at a time on the page “0” and the column 2 of the display RAM 23, and then the column address is as increased by “1”, automatically. Thereafter, when 8-bit data is transferred and a write command is received, 8-bit data is written on the page “0” and the column 3 of the display RAM 23. In the same way, in response to the write commands of 3×24 times, a content of the display RAM 23 is newly changed.
Then, for the read operation, the controller 28 controls the common driver circuit 21 and the segment driver circuit 22 to display data stored in the display RAM 23 on the display panel 10. More specifically, the controller 28 designates a line address through the line address generating circuit 26 and thereafter stores 24-bit data of a designated row at a time in the 24-bit data latch circuit 25. In FIG. 2, an 18th row is designated. The controller 28 sends a signal so that the common driver circuit 21 may scan the designated row (i.e., the 18th row ) of the display panel 10 so that 24-bit data in the 24-bit latch circuit 25 may be applied to the display panel 10 through the segment driver circuit 22. That is, when the common driver circuit 21 scans the 18th row of the display panel 10, the data latch circuit 25 latches the 24-bit data of the 18th row and outputs this data through the segment driver circuit 22 to the display panel 10.
FIG. 3A shows a display state when the display data are displayed in the typical display control system of FIG. 1, and FIG. 3B shows a display state when the display data are displayed in the conventional organic EL display control system of FIG. 2. In FIGS. 3A and 3B, a portion of the display data defined by a dotted line represents the 24-bit data of the 18th row.
As shown in FIG. 3A, in the case of the display control system of FIG. 1, the display data is horizontally, i.e., properly, displayed. However, as shown in FIG. 3B, in case of the organic EL display control system of FIG. 2, the display data is vertically displayed on the display panel 10. That is, the display data is displayed in a vertical form because the common terminal is changed in position with the segment terminal. In other words, in the typical display control system of FIG. 1, the segment driver circuit 22 is connected to the segment terminal arranged on a lower portion, and thus the display data is horizontally applied to the display panel 10. However, in the conventional organic EL display control system of FIG. 2, the segment driver circuit 22 is connected to the segment terminal arranged on a side portion of the display panel 10, and thus the display data is vertically applied to the display panel 10. As a result, the display data to be horizontally displayed is vertically displayed.
In order to overcome the above problems, display data should be output from the display RAM 23 and then applied to the display panel 10 in consideration of an output form of the display data from the display RAM 23 and a position of the segment terminal in the display panel 10.
If data stored in the display RAM 23 are textures, the display data can properly be displayed by changing software or algorithms. However, if data written on the display RAM 23 are images of, for example, a videophone, since images should be properly turned, it is a very heavy task to change software or algorithms of images. In addition, in order to properly display image data, not only should the software be changed, but also hardware components such as a buffer RAM should be added.